Off grid shed?

[Colin33]

I'm planning the electrics for my shed/summer house which is in a field miles away from mains electric. I want to run some 12v led filament lamps along with some 12v Gu10's. Total of around 50W (4A) Also some usb outlets for phone charging etc, and maybe a caravan style water pump for intermittent use.
Although I'm 2399 qualified, I've only ever fitted my own home grid tied system so have little experience with off grid stuff. My question is, can I use a couple of 250w 30v panels like I use at home, and an MPPT controller similar to this to charge a couple of leisure batteries? : 40A LCD MPPT Solar Panel Battery Charge Controller 12V/24V Auto Z-bracket Set SP | eBay - http://www.ebay.co.uk/itm/40A-LCD-MPPT-Solar-Panel-Battery-Charge-Controller-12V-24V-Auto-Z-bracket-Set-SP-/382227755272?hash=item58fe8cb108:g:RTsAAOSwImRYJBRD

If so, if the panels are wired in series (60v output) will this controller happily take this voltage and in turn take it down to the voltage required to charge my 12v batteries?
Any advice gratefully received before I start experimenting

 

[Worcester]

Give the guys at Wind & Sun a call, or Fred at Hollybrook Power Supplies. Fred does loads of off grid stuff, caravans, houseboats etc

 

[Midwest]

Wot you doing in a shed miles away from civilisation

 

[buzzlightyear]

possible knitting class .

 

[dmxtothemax]

QUOTE - [ I'm planning the electrics for my shed/summer house which is in a field miles away from mains electric. I want to run some 12v led filament lamps along with some 12v Gu10's. Total of around 50W (4A) Also some usb outlets for phone charging etc, and maybe a caravan style water pump for intermittent use.
My question is, can I use a couple of 250w 30v panels like I use at home, and an MPPT controller similar to this to charge a couple of leisure batteries? : 40A LCD MPPT Solar Panel Battery Charge Controller 12V/24V Auto Z-bracket Set SP | eBay - http://www.ebay.co.uk/itm/40A-LCD-MPPT-Solar-Panel-Battery-Charge-Controller-12V-24V-Auto-Z-bracket-Set-SP-/382227755272?hash=item58fe8cb108:g:RTsAAOSwImRYJBRD ]

ANSWER = YES !

If so, if the panels are wired in series (60v output) will this controller happily take this voltage and in turn take it down to the voltage required to charge my 12v batteries?

WHY ?
why series, this may or may not work, depending on the spec's of you regulator,
either way the regulator will be working real hard, it's a BAD idea.
parrallel is better.

What are "Leisure batteries", how well the system works, comes down to the quality of the batteries, normal 12v batteries (shallow dis-charge) will work, but not well, you should consider proper deep dis-charge batteries, they will work better and for longer.

 

[Colin33]

Thanks dmx, I suppose like a domestic system in the Uk the voltage is kept high to reduce the current for cable sizing. So I assume with just two panels this is not necessary, although I think this particular charge controller is ok for 100v. As for batteries, I will start with what I have, a couple of car batteries but will upgrade these when they die. I think the controller in the link above has the option to change the parameters so the battery voltage at which the system shuts down can be altered to prevent the battery voltage falling too low....

 

[davesparks]

What are "Leisure batteries",

Leisure batteries are the batteries used in leisure vehicles like motorhomes and caravans, basically a deep discharge version of a car battery.

 

[dmxtothemax]

Your proposed system is small and low powered,
But that is all you need for your requirements.
Even one panel would probably do this job.
I still think using 2 panels in series is just wastefull.
The panel voltage as it is (30v), is already well above the required voltage to charge a 12v battery, which needs only 14.4v.
Any losses in your system will be minimal
as it is only quite small.

If your leisure batteries are deep cycle then they will be just fine.
Let us know how it goes ?

 

[arklan]

made an account just to reply to this thread!
ok so the reason why you want the voltage to be high is because a lot of mppts arent buck boost, they are just buck.
so to get the most out of your panels you want the voltage to be high as possible so that you get power for a longer part of the day.
so when the sun goes down it continues to give you that little bit extra.
on the charge controller linked, putting the 2 panels in series is absolutely the best way to go and wont damage or stress it at all.

 

[Colin33]

made an account just to reply to this thread!
ok so the reason why you want the voltage to be high is because a lot of mppts arent buck boost, they are just buck.
so to get the most out of your panels you want the voltage to be high as possible so that you get power for a longer part of the day.
so when the sun goes down it continues to give you that little bit extra.
on the charge controller linked, putting the 2 panels in series is absolutely the best way to go and wont damage or stress it at all.

Welcome to the Forum Arklan.
I was thinking along these lines myself, but have come to the conclusion that it will be simple with just two panels to swop from parallel to series, or vice versa and monitor the results. I'm still working on the structure so will not be fitting the panels for a while but will let you know the results when I'm done..

 

[Worcester]

Voltage (Voc) doesn't change much with irradiance, it is primarily the current that changes.

Morningstar Charge Controllers | Wind & Sun - http://www.windandsun.co.uk/products/Solar-Charge-Controllers-/Morningstar-Charge-Controllers#.Wcg5A2iPJPY